Words and Photos: Chris Wastell
In this article, Chris Wastell talks about his experience with a couple of Moto Guzzis – from the same era, but quite the contrast.
A bit of background on the 500cc Guzzis
There is no doubting the brilliance of Carlo Guzzi. As an aircraft mechanic and driver during the First World War, he came into contact with a couple of pilots who shared the same passion for motorcycles, and the trio then planned to do business once the war had ended. Guzzi had already designed his ideal motorcycle but had abandoned it to join the army at the outbreak of war, where he later transferred to the Air Force.
In the new founded company, it was natural that Guzzi would be the designer. Giovanni Ravelli, already known as a pre-war racer, would compete their product for publicity whilst Giorgio Parodi would provide the finance via a loan from his father, a wealthy Genoese shipping magnate. Tragically, Ravelli was killed in a flying accident before the venture got under way and it is in his memory that the Italian Air Force Eagle is incorporated in the company badge.
In the 1920s, 500cc was regarded as the ideal capacity for a medium-sized engine with enough power-to-weight for a motorcycle to fulfil most needs. Carlo went one further by designing his engine with a horizontal cylinder, keeping the cylinder head cool in the air flow whilst providing a very low centre of gravity. Not only that, but he also went against convention by making it ‘over-square’ (88mm bore with 82mm stroke) which reduced the stress on the needle roller big end and allowed for higher engine revolutions. The huge external flywheel makes a narrow engine possible which is easy to start due to the inertia generated from it. The engine runs backwards which enables a clever, efficient splash lubrication; if it ran forwards in the conventional fashion, the system would not work. From a separate oil tank which is cooled by airflow – not only the engine and unit-construction gearbox, but also the clutch and final drive chain are lubricated (in addition to the rider’s back!).
Moto Guzzi Models in the 1930s
In the 1930s customers were able to opt for a bike with a side-valve inlet/overhead-valve exhaust motor, or a full-on overhead-valve model. Chris Wastell has had the chance to experience both machines on a 1936 GTS and a 1936 GTV – here is little about these bikes.
The Moto Guzzi GTS
The GTS is the sprung-frame version of Guzzi’s rigid-framed ‘Type S’ (both manufactured from 1934 to 1940) which in turn, was a development of the earlier Sport 15, introduced in 1931.
They had much the same 500cc side-valve inlet/overhead-valve exhaust engine but now with a 4-speed foot-change gearbox. The option remained, of hand-change on the S model for those who distrusted innovation. The engine is made to produce 13.2 hp at 4,000 revs giving a top speed of 65mph.
In an era where most bikes had to be hauled onto rear-mounted stands, Moto Guzzi had a perfectly balanced roll-on centre stand. Physically, the bikes are very small and not for six-footers!
The Moto Guzzi GTV
At the same time as the GTS, the V (Rigid) and GTV (Spring Frame) were listed, and featured a much-improved overhead-valve engine which produced 18hp and a top speed of over 74mph.
The unorthodox but highly effective, rear suspension was designed in 1927 by Carlo and his elder brother, Giuseppe. It employs a set of large springs in a horizontal box beneath the engine, whilst damping is provided by friction discs in the unusual looking cantilever supports. In the author’s opinion, these are the best handling bikes of their era. Stanley Woods won both the lightweight and Senior Isle of Man TT in 1935.
My Story with the GTV
The GTV shown here was registered in UK by me and foolishly sold a couple of years back. It was built by a chap in Italy who was married to an English woman called Rita, which he named the bike. Later down the line, he separated from Rita and went on to live the dream single life: most of the ground floor of his medieval house was a garage with the rest used for making wine from his own vineyard. He had a collection of Guzzi’s and scooters, however one day he had an accident and fell off it, snapping the gear-change pedal, and after that he never rode a bike again. The owner eventually passed and his son went over and brought the bike back with him, where it then sat in his shed for around ten years. He used to start it a couple of times a year until inevitably, the magneto packed up. Covid unfortunately took its toll on his chauffeur business and with little experience working on these bikes, he had to release the Guzzi in return for cash, which is where I came in.
The GTV Rebuild!
Once the magneto was rebuilt, the bike ran OK and I completed the Bristol Distinguished Gentleman’s Run on it. On the way home, the exhaust valve seized and I pulled over on the side of the road, followed five minutes later by a transit van. Driving the van was chap called Chris Tait, on his way home from the same run with a Norton in the back. Without hesitation, he insisted on taking me home, 20 miles in the opposite direction he was going in! It turned out, he had rescued me with a dead mag on a Super Alce a couple of years earlier when he had been a professional recovery driver.
On inspection, I found the valve seized in the guide and the guide pulled about 1/4inch out of the head. The guide appeared very worn, so I took the whole head to South Cerney engineering who focus on old stuff. The bore had a deep score down it, so I had a rebore and sourced a NOS piston from Italy. I put it all back together and rode gently for about eight miles before the valve seized again. The valve has a lash cap which sits atop the valve to take the wear of the rocker, and unfortunately when the valve seizes, this little cap is lost on the road. A friend rescued me with his trailer.
I returned to Cerney Engineering and though surprised, they bored the guide out a bit further. The engine was pieced back together once more, and I was back on another test ride. About 2 miles from home there is a large, busy roundabout so I planned a simple loop. Wrong! I reached the roundabout and the lash cap obviously went west. At a leisurely walking pace, I managed to get home in 2nd gear with an articulated lorry up my backside. The valve must have seized momentarily, long enough to loosen the cap. Without that vital piece the valve clearance is about 5mm! I fitted a replacement cap (by now I had turned a stock of spares on the lathe).
Another test ride: 300 yards along the lane from home and anther valve seizure. This time, the guide was pulled loose again. Some in-depth research revealed Moto Guzzi’s original spec. for valve to guide clearance and it was huge. I took the printout with me to Cerney Engineering who were incredulous and took some persuasion to do the job.
Time for another test run. The engine fired straight up but after about 20 seconds started popping. I rode very gently up the lane, about a mile and back. There was no power to the engine. I took the head off again to find it had three cracks radiating from the new valve guide. It was back to Cerney.
Cerney Engineering were honourable and sent the head to specialist welder in the Midlands. I returned home with a head that was no better than new, and realised that I hadn’t got the rocker box studs which had been removed by the welders. It was back to Cerney to collect the studs and they provided me with some super strong, heat-resistant thread lock to fit them with.
What now followed was 500 miles of very careful running in through early summer. I wheeled the Guzzi out into the sunshine ready for a VMCC run. Finding Top Dead Centre prior to starting, there was a metallic clunk and the engine felt solid. I removed the head to find that exhaust valve seat has dropped out. It was back to Cerney who fit a new seat and peen it in place. We are now in business! That was until late summer and another VMCC run when the engine stuttered and died. Seven and a half hours later, the insurance recovery arrived to take me home, 45 minutes away. This time, the tapered drive end of the Marelli magneto has sheared. These are rare in the UK but a friendly Frenchman came to the rescue with a replacement taper and in no time, we were back on the road.
There was nothing else to let Rita down, but I foolishly decided that I needed something I could ride through winter without worrying about the chrome so I advertised her for sale and off the bike went to Yorkshire.
Keeping them Alive
As these two Moto Guzzis show, even machines built in the same year can present wildly different mechanical personalities – one rewards with simplicity, the other has a sprinkle of complexity. But it is in overcoming these stubborn problems, tracing faults, and coaxing life back into ageing metal that we find the real joy. As Chris demonstrates in this article, the journey is certainly not always smooth, but for those who persevere, it is exactly what makes these machines enduring and unforgettable.
an article by Chris Wastell for The Girder Club
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